Navegando por Palavras-chave "Aporphine alkaloid"

Agora exibindo 1 - 2 de 2
  • Imagem de Miniatura
    Item
    Acesso aberto (Open Access)
    Estudo visando à síntese total da (S)-nuciferina
    (Universidade Federal de São Paulo, 2018-05-04) Silva, Tamiris Reissa Cipriano da [UNIFESP]; Raminelli, Cristiano [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Considering bioactive natural products, aporphine alkaloids compose an important class of compounds that acts as dopamine receptor ligands. In addition, some of these alkaloids, among which we stand out (±)-nuciferine, have presented selective blockade of serotonin 5-HT2A receptor, which in therapeutic terms is related to various disorders, including schizophrenia, insomnia, and ischemic heart disease. Furthermore, aporphine alkaloids have other important biological activities, including, for example, anti-HIV and antineoplastic activities. Having in mind the great biological importance of this class of natural products, we have worked in the enantioselective total synthesis of (S)-nuciferine, through a novel approach to obtain chiral aporphine alkaloids, employing in key steps of the synthesis [4 + 2] cycloaddition reaction followed by hydrogen migration, via benzyne chemistry under mild conditions, and enantioselective hydrogenation reaction, using hydrogen in the presence of catalytic amount of noble metal complex (Ru, Rh, and Ir) containing chiral ligand (monodentate and bidentate). Although (S)-nuciferine has not been achieved, the study of enantioselective reduction reactions afforded relevant information about the stability of dehydroaporphine skeletons and allowed the expansion by searching of better conditions to complete the synthesis in the future.
  • Imagem de Miniatura
    Item
    Acesso aberto (Open Access)
    Síntese total do alcaloide aporfioide (R)-(-)-aporfina
    (Universidade Federal de São Paulo, 2015-07-30) Perecim, Givago Prado [UNIFESP]; Raminelli, Cristiano [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The benzyne chemistry have been successfully employed in various approaches involving total synthesis of natural products and bioactive substances. Thus, due to the considerable importance of 2-(trimethylsilyl)aryl triflates in the current context of benzyne chemistry, as well as due to the pronounced biological activities presented by aporphine alkaloids, including the potential of such compounds as agonists of dopaminergic receptors and, for instance, their anticancer, anti-HIV and antileishmanial activities, we decided to accomplish the total synthesis of the aporphine alkaloid (R)-(-)-aporphine, employing a strategy that presents a sequence of reactions, namely, [4 + 2] cycloaddition reaction followed by a hydrogen migration, which leads to the formation of the aporphine core. In this sense, we submit 1-methylene-1,2,3,4-tetrahydroisoquinoline to the reaction with benzyne, formed from 2-(trimethylsilyl)phenyl triflate, under relatively mild reaction conditions using CsF as base and MeCN as solvent. Afterwards, the key intermediate resulted from the [4 + 2] cycloaddition reaction followed by a hydrogen migration, which contains the aporphine core, was subjected to functional group transformations resulting in the aporphine alkaloid of interest (R)-(-)-aporphine, which was obtained in seven steps with an overall yield of 11%.